Some of you took umbrage with my saying that I’m skeptical of menu-labeling for obesity prevention. I get your main point – that this shouldn’t be so hard. Yet it is, for many reasons. There’s a new study in JAMA that shows one reason why:
Context National recommendations for the prevention and treatment of obesity emphasize reducing energy intake. Foods purchased in restaurants provide approximately 35% of the daily energy intake in US individuals but the accuracy of the energy contents listed for these foods is unknown.
Objective To examine the accuracy of stated energy contents of foods purchased in restaurants.
Design and Setting A validated bomb calorimetry technique was used to measure dietary energy in food from 42 restaurants, comprising 269 total food items and 242 unique foods. The restaurants and foods were randomly selected from quick-serve and sit-down restaurants in Massachusetts, Arkansas, and Indiana between January and June 2010.
Main Outcome Measure The difference between restaurant-stated and laboratory-measured energy contents, which were corrected for standard metabolizable energy conversion factors.
Gotta love studies like these. Researchers went into restaurants with menu-labeling and bought their food. Then they took them to the lab and measured how close the stated caloric content was to the actual caloric content. To be eligible, a restaurant had to be in a chain with sales placing them in the top 400 in 2008, and had to be either “quick-serve” or “sit-down”. They also had to have calorie content reported on their website.
How accurately did they report the calories in their food items?
Well, overall, they were pretty accurate. But individual items showed a lot more variation. Of the 269 food items that were measured, almost 20% had 100 or more actual calories than what was stated. The worst offender, a side dish, had more than 1000 calories in a portion that was reported to have only 450 calories.
Now it’s possible that the researchers got a bad sample. Perhaps their was an overeager server that night who gave them more than they were supposed to get. So, in the interest of accuracy, the researchers took some of the worst offenders, and went back and got a second sample. They were able to do this for 13 of the 17 foods with foods with the largest discrepancies between the reported and measured calories. In the first pass, these food items had 289 more calories on average than reported. In the second look, they still had 258 more calories than reported. Most concerning for those trying to watch what they eat, the food items with lower reported calories (ie healthy or diet items) were significantly more likely to have higher calories than reported. This was balanced, oddly enough, but the high-reported calorie foods having fewer calories than reported.
Now, this isn’t to say that I think the restaurants were lying. But if you’re a chain, there is bound to be some variation in portion sizes and contents. Calories will vary, sometimes significantly.
If you want to be positive of something, you have to make it yourself. I still say the secret to weight loss is: eat less, and exercise.